ln/ln.c

   1 /*
   2  * Copyright (c) 1987, 1993, 1994
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 3. All advertising materials mentioning features or use of this software
  14  *    must display the following acknowledgement:
  15  *      This product includes software developed by the University of
  16  *      California, Berkeley and its contributors.
  17  * 4. Neither the name of the University nor the names of its contributors
  18  *    may be used to endorse or promote products derived from this software
  19  *    without specific prior written permission.
  20  *
  21  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  22  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  23  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  24  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  25  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  26  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  27  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  28  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  29  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  30  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  31  * SUCH DAMAGE.
  32  */
  33
  34 #ifndef lint
  35 static char const copyright[] =
  36 "@(#) Copyright (c) 1987, 1993, 1994\n\
  37         The Regents of the University of California.  All rights reserved.\n";
  38 #endif /* not lint */
  39
  40 #ifndef lint
  41 #if 0
  42 static char sccsid[] = "@(#)ln.c        8.2 (Berkeley) 3/31/94";
  43 #endif
  44 #endif /* not lint */
  45 #include <sys/cdefs.h>
  46 __RCSID("$FreeBSD: src/bin/ln/ln.c,v 1.29 2002/07/31 16:53:59 markm Exp $");
  47
  48 #include <sys/param.h>
  49 #include <sys/stat.h>
  50
  51 #include <err.h>
  52 #include <errno.h>
  53 #include <limits.h>
  54 #include <stdio.h>
  55 #include <stdlib.h>
  56 #include <string.h>
  57 #include <unistd.h>
  58
  59 int     fflag;                          /* Unlink existing files. */
  60 int     hflag;                          /* Check new name for symlink first. */
  61 int     iflag;                          /* Interactive mode. */
  62 int     sflag;                          /* Symbolic, not hard, link. */
  63 int     vflag;                          /* Verbose output. */
  64                                         /* System link call. */
  65 int (*linkf)(const char *, const char *);
  66 char    linkch;
  67
  68 int     linkit(const char *, const char *, int);
  69 void    usage(void);
  70
  71 int
  72 main(int argc, char *argv[])
  73 {
  74         struct stat sb;
  75         char *p, *sourcedir;
  76         int ch, exitval;
  77
  78         /*
  79          * Test for the special case where the utility is called as
  80          * "link", for which the functionality provided is greatly
  81          * simplified.
  82          */
  83         if ((p = rindex(argv[0], '/')) == NULL)
  84                 p = argv[0];
  85         else
  86                 ++p;
  87         if (strcmp(p, "link") == 0) {
  88                 while (getopt(argc, argv, "") != -1)
  89                         usage();
  90                 argc -= optind;
  91                 argv += optind;
  92                 if (argc != 2)
  93                         usage();
  94                 linkf = link;
  95                 exit(linkit(argv[0], argv[1], 0));
  96         }
  97
  98         while ((ch = getopt(argc, argv, "fhinsv")) != -1)
  99                 switch (ch) {
 100                 case 'f':
 101                         fflag = 1;
 102                         iflag = 0;
 103                         break;
 104                 case 'h':
 105                 case 'n':
 106                         hflag = 1;
 107                         break;
 108                 case 'i':
 109                         iflag = 1;
 110                         fflag = 0;
 111                         break;
 112                 case 's':
 113                         sflag = 1;
 114                         break;
 115                 case 'v':
 116                         vflag = 1;
 117                         break;
 118                 case '?':
 119                 default:
 120                         usage();
 121                 }
 122
 123         argv += optind;
 124         argc -= optind;
 125
 126         linkf = sflag ? symlink : link;
 127         linkch = sflag ? '-' : '=';
 128
 129         switch(argc) {
 130         case 0:
 131                 usage();
 132                 /* NOTREACHED */
 133         case 1:                         /* ln target */
 134                 exit(linkit(argv[0], ".", 1));
 135         case 2:                         /* ln target source */
 136                 exit(linkit(argv[0], argv[1], 0));
 137         default:
 138                 ;
 139         }
 140                                         /* ln target1 target2 directory */
 141         sourcedir = argv[argc - 1];
 142         if (hflag && lstat(sourcedir, &sb) == 0 && S_ISLNK(sb.st_mode)) {
 143                 /*
 144                  * We were asked not to follow symlinks, but found one at
 145                  * the target--simulate "not a directory" error
 146                  */
 147                 errno = ENOTDIR;
 148                 err(1, "%s", sourcedir);
 149         }
 150         if (stat(sourcedir, &sb))
 151                 err(1, "%s", sourcedir);
 152         if (!S_ISDIR(sb.st_mode))
 153                 usage();
 154         for (exitval = 0; *argv != sourcedir; ++argv)
 155                 exitval |= linkit(*argv, sourcedir, 1);
 156         exit(exitval);
 157 }
 158
 159 int
 160 linkit(const char *target, const char *source, int isdir)
 161 {
 162         struct stat sb;
 163         const char *p;
 164         int ch, exists, first;
 165         char path[PATH_MAX];
 166
 167         if (!sflag) {
 168                 /* If target doesn't exist, quit now. */
 169                 if (stat(target, &sb)) {
 170                         warn("%s", target);
 171                         return (1);
 172                 }
 173                 /* Only symbolic links to directories. */
 174                 if (S_ISDIR(sb.st_mode)) {
 175                         errno = EISDIR;
 176                         warn("%s", target);
 177                         return (1);
 178                 }
 179         }
 180
 181         /*
 182          * If the source is a directory (and not a symlink if hflag),
 183          * append the target's name.
 184          */
 185         if (isdir ||
 186             (lstat(source, &sb) == 0 && S_ISDIR(sb.st_mode)) ||
 187             (!hflag && stat(source, &sb) == 0 && S_ISDIR(sb.st_mode))) {
 188                 if ((p = strrchr(target, '/')) == NULL)
 189                         p = target;
 190                 else
 191                         ++p;
 192                 if (snprintf(path, sizeof(path), "%s/%s", source, p) >=
 193                     (ssize_t)sizeof(path)) {
 194                         errno = ENAMETOOLONG;
 195                         warn("%s", target);
 196                         return (1);
 197                 }
 198                 source = path;
 199         }
 200
 201         exists = !lstat(source, &sb);
 202         /*
 203          * If the file exists, then unlink it forcibly if -f was specified
 204          * and interactively if -i was specified.
 205          */
 206         if (fflag && exists) {
 207                 if (unlink(source)) {
 208                         warn("%s", source);
 209                         return (1);
 210                 }
 211         } else if (iflag && exists) {
 212                 fflush(stdout);
 213                 fprintf(stderr, "replace %s? ", source);
 214
 215                 first = ch = getchar();
 216                 while(ch != '\n' && ch != EOF)
 217                         ch = getchar();
 218                 if (first != 'y' && first != 'Y') {
 219                         fprintf(stderr, "not replaced\n");
 220                         return (1);
 221                 }
 222
 223                 if (unlink(source)) {
 224                         warn("%s", source);
 225                         return (1);
 226                 }
 227         }
 228
 229         /* Attempt the link. */
 230         if ((*linkf)(target, source)) {
 231                 warn("%s", source);
 232                 return (1);
 233         }
 234         if (vflag)
 235                 (void)printf("%s %c> %s\n", source, linkch, target);
 236         return (0);
 237 }
 238
 239 void
 240 usage(void)
 241 {
 242         (void)fprintf(stderr, "%s\n%s\n%s\n",
 243             "usage: ln [-fhinsv] file1 file2",
 244             "       ln [-fhinsv] file ... directory",
 245             "       link file1 file2");
 246         exit(1);
 247 }